In aging men, mosaic loss of chromosome Y (mLOY) is a possible biomarker for increased risk of disease, including Alzheimer disease (AD). We previously reported mLOY increased with age and carriers of mLOY had an increased risk of AD. We also found plasma Aβ42/p-tau181 ratio (APR) was significantly lower among AD Amish individuals compared to cognitively-unimpaired (CU) individuals. We now examine how these two biomarkers interplay with cognitive status in Amish males. mLOY was determined using the Mosaic Chromosomal Alterations(MoChA) pipeline. Extensive QC was done for both mLOY and plasma biomarker measures. Consensus review of medical history and neuropsychological testing categorized individuals into AD, Mild-cognitive-impairment (MCI) or Cognitive-impairment-not-AD (CINAD) or CU. The cognitively-impaired (CI) group combined AD, MCI and CINAD. We compared 1) CI to CU and 2) AD to CU. Correlation between APR and mLOY were estimated accounting for relatedness. Receiver operating characteristic analysis was performed to evaluate the discriminatory ability of the two biomarkers compared to the baseline model with age and presence/absence of APOE ε4 alleles. p -value <0.05 was noted as statistically significant. 249 males (mean age=82.89±5.57) had measurements for both biomarkers. Of these, a subset had consensus diagnoses AD ( n  = 30; mean age=85.63±5.31), CINAD, MCI or CU ( n  = 105; mean age=82.01±5.36). The mean age of 82 CI individuals was 84.34±4.73. mLOY was observed in 20.1% of CU vs. 29.3% of CI ( p -value=0.23). APR was significantly negatively correlated with CI and AD as expected, was positively correlated with mLOY but not significantly and remained positively correlated when stratified, with the stronger correlation in AD. For AD, the area under the curve (AUC) improved from 0.70 to 0.82 with the inclusion of APR, with mLOY showing little effect. For CI, AUC improved from 0.63 to 0.68 by including mLOY, with no independent effect of APR. When including both in the model, AUC improves from 0.63 to 0.69. We observed two promising biomarkers of AD, mLOY and APR, both contribute discriminating AD and CI but differently. This and the stringer correlation in AD may indicate they are more specific to AD than non-specific CI.

INTRODUCTION:Cognitive SuperAgers (SAs) are individuals aged 80+ with exceptional episodic memory performance for their age, exceeding middle-aged adult norms. This study integrates family- and association-based methods to identify genetic variants associated with SAs in the Midwestern Amish population. METHODS:Eighty-three Amish SAs were grouped into 16 pedigrees for parametric and non-parametric linkage analysis. Variants in linked regions (heterogeneity logarithm of the odds [HLOD] or Kong and Cox logarithm of the odds [LOD*] ≥ 3) were tested for association with SAs using two contrasts: SA versus Alzheimer's disease (AD; n = 40) and SA versus cognitively unimpaired (CU), age-matched non-SA individuals (CU80+; n = 157). RESULTS:Evidence of linkage for SAs was observed on chromosomes 1, 2, 7, 16, and 20, with the strongest signal around the AD-associated locus WDR12 on chromosome 2. Association analysis for SA versus AD identified eight variants in HIVEP3 (chromosome 1) that were nominally significant when comparing SA versus CU80+. DISCUSSION:WDR12 and HIVEP3 are potential candidate genes contributing to SAs in the Amish population.

BACKGROUND:In Apathy in Dementia Methylphenidate Trial 2 (ADMET2), apathy in Alzheimer's disease improved with methylphenidate (MPH) in a randomized, placebo-controlled trial, though response varied. Here we evaluated serum biomarkers for their association with apathy and with treatment response. METHODS:All ADMET2 participants with available blood samples were included. Markers of inflammation [interleukin (IL)-6, IL-10, Tumor Necrosis Factor (TNF)], oxidative stress [lipid hydroperoxide (LPH), 4-hydroxynonenal (4-HNE), 8-isoprostane (8-ISO)] and neuronal injury [neurofilament light (NfL), S100B] were assessed and values log-transformed. Neuropsychiatric Inventory-apathy (NPI-A) measured apathy. Least Absolute Shrinkage and Selection Operator (LASSO) regression was performed for feature selection of baseline markers predicting NPI-A at Month-6 (M6). Univariate analyses examined individual biomarker effects and multivariable models evaluated their combined effects. Treatment interactions, baseline and change in biomarker levels in treatment responders (≥4 change in NPI-A) and remitters (M6 NPI-A=0) were explored. RESULTS:In the ADMET2 biomarker subset (n = 44, MPH:21, age:75 years, MMSE:20.2), higher baseline TNF was associated with higher M6 NPI-A [B(SE)= 6.86 (1.71), p = .0003], and multivariable models found lower baseline TNF [B(SE)= 8.28(1.61), p < .001] and higher baseline S100B [B(SE)= -6.41(1.95), p = .002] were associated with lower M6 NPI-A. Exploratory analyses suggested that higher baseline NfL significantly interacted with treatment to predict lower M6 NPI-A [B(SE)= -8.36(4.21), p = .05], only when adjusting for cognition. MPH remitters had lower baseline TNF [B(SE)= -0.27(0.10), p = .02], higher baseline NfL [B(SE)= 0.33(0.14), p = .03], and a greater decrease in IL-6 [B(SE)= -0.44 (0.17), p = .02]. CONCLUSIONS:Inflammatory and neuronal injury biomarkers may have prognostic value and may potentially inform treatment response and remission outcomes in apathy. Apathy in Dementia Methylphenidate Trial 2 (ADMET2), NCT02346201, https://clinicaltrials.gov/study/NCT02346201.

INTRODUCTION:Plasma biomarkers for Alzheimer's disease (AD) hold promise for disease diagnosis and prediction, yet their genetic underpinnings remain under explored. METHODS:We measured plasma amyloid beta (Aβ)40, Aβ42, Aβ42/Aβ40, total tau (t-tau), phosphorylated tau 181 (p-tau181), Aβ42/t-tau, Aβ42/p-tau181, neurofilament light chain, and glial fibrillary acidic protein in the Midwestern Amish. Pedigree-based heritability ( h ped 2 ) was estimated from multigenerational pedigrees, and single nucleotide polymorphism (SNP)-based heritability ( h SNP 2 ) was derived from SNPs. RESULTS:Among all Amish individuals, additive genetic effects ( h ped 2 ) explained 11.1% to 36.6% of biomarker variances. h SNP 2 estimates were consistently lower, ranging from 6.7% to 28.7%. The heritability of these biomarkers in subgroups of cognitively normal individuals and apolipoprotein E ε4 non-carriers yielded similar results. DISCUSSION:Plasma biomarkers such as Aβ, t-tau, and p-tau181 are moderately heritable in the Amish, underscoring the impact of genetic determinants of plasma biomarkers associated with AD.

Apathy is a prevalent neuropsychiatric symptom (NPS) in Alzheimer’s disease (AD), linked to functional impairment and reduced quality of life. The Apathy in Dementia Methylphenidate Trial 2 (ADMET-2) found methylphenidate (MPH) had modest efficacy for treating apathy, but treatment responses varied. MPH blocks dopamine and noradrenaline transporters, inhibiting dopamine and noradrenaline reuptake. Lipids are closely tied to monamine transporter function through their structural and signaling roles in neurotransmission, neuroinflammation, and synaptic plasticity. This study aimed to identify lipid species associated with MPH response and explore lipid pathway disruptions in responders versus non-responders. Participants from ADMET-2 with baseline lipidomic data were included. Responders were defined by a ≥4-point improvement on the Neuropsychiatric Inventory Apathy subscale (NPI-A), or moderate-to-marked improvement on the ADCS-Clinicians Global Impression-Change (ADCS-CGIC). Baseline plasma samples underwent lipidomic profiling. Sparse Partial Least Squares Discriminant Analysis (sPLS-DA) in the MPH group was used to identify lipid species distinguishing responders from non-responders. Model performance was evaluated by area under the curve (AUC). Identified lipid species were analyzed in MetaboAnalyst for pathway enrichment. A secondary analysis in the placebo group assessed specificity of findings to MPH. Of the 43 MPH-treated participants, 28 were NPI-apathy responders, and 10 were ADCS-CGIC responders. The PLS-DA model achieved robust discrimination between responders and non-responders (NPI-apathy: AUC = 0.82 +/- 0.05; ADCS-CGIC: AUC=0.84 +/- 0.07). Pathway analysis revealed disruptions in ceramide, phosphosphingolipid, and glycosphingolipid metabolism for NPI-apathy responders, and ceramide and glycosphingolipid metabolism for ADCS-CGIC responders. In 55 placebo-treated participants (30 NPI-apathy responders), an AUC of 0.79 +/- 0.05 was achieved, with pathway analysis indicating disruption in glycosphingolipid metabolism only. This study demonstrates the utility of lipidomic profiling in identifying biomarkers of response to MPH in AD patients with apathy. The identified lipidomic species are broadly related to monoamine transporter function, reflecting their role in neurotransmission and synaptic plasticity. While glycosphingolipid metabolism appears broadly linked to changes in apathy, disruptions in ceramide and phospholipid metabolism may be specific to MPH treatment. Further study of these pathways may offer insights into the molecular mechanisms underlying apathy and treatment response, and could inform future biomarker-guided interventions.

Late-onset Alzheimer disease (LOAD), the most common form of dementia among older adults, is a neurodegenerative disease characterized by brain amyloid-β (Aβ) plaque deposition and neurofibrillary tangles. The causes of LOAD are not known but several recent lines of evidence implicate the adaptive immune system. Here, we sought to characterize somatic T-cell receptor (TCR) sequence diversity profiles and class I and II human leukocyte antigen (HLA) alleles from DNA extracted from peripheral tissues from Midwestern Amish participating in longitudinal studies of aging. We immunosequenced the TCR beta chain from genomic DNA of 72 Midwestern Amish, including participants with clinically diagnosed LOAD (n=6), mild cognitive impairment (MCI; n=16), cognitive impairment but not AD (CINAD; n=3), and 35 cognitively unaffected. TCR sequence diversity by cognitive status was examined using a variety of metrics, and tests of association were performed between cognitive status and HLA alleles. For a subset of participants, plasma biomarkers for LOAD pathogenesis were available to evaluate TCR sequence diversity by cognitive status. TCR sequence diversity measured as Simpson's clonality was lower among LOAD+MCI compared with non-LOAD, but these differences were not independent of age. Relatively few clonotypes (exact nucleotide sequences) were shared across participants; of those few shared include the Epstein Barr virus associated clonotype. HLA-A*03:01 and several HLA-DRB1 alleles were under-represented among LOAD+MCI participants compared with cognitively unaffected participants, but these associations were no longer significant in adjusted analyses. Among LOAD+MCI participants with plasma biomarkers, increased p-tau181 was associated decreased TCR sequence diversity, and the association was independent of age. In this limited Midwestern Amish sample, the observed TCR diversity associations are consistent with the involvement of the adaptive immune system in LOAD.

Background: Genetic studies of Alzheimer's disease (AD) have made remarkable progress in identifying genetic factors that increase the risk of AD. However, the genetic determinants that contribute to preserved cognition at older ages, particularly those that mitigate AD risk, are less understood. In the Midwestern Amish community, certain older adults maintain normal cognitive abilities despite carrying a relatively high genetic risk of AD. Our goal was to identify shared genetic factors among high-risk Amish sibships enriched with cognitively unimpaired individuals. We hypothesized that ranking sibships by their mean genetic risk of AD would provide greater evidence of genetic linkage in cognitively preserved sibships at higher risk, identifying genomic regions containing protective loci. Methods: Cognitive status in adult Amish participants (n = 1,855) was evaluated using the Modified Mini Mental Status Exam (3MS). Those aged ≥75 with education-adjusted 3MS scores ≥87 were classified as cognitively unimpaired (CU), while those with education-adjusted 3MS scores below 87 were classified as cognitively impaired (CI). Genome-wide non-parametric linkage analysis was performed on 143 sibships with at least two CU members. To account for known genetic risk, ordered-subsets analysis (OSA) was used to rank families by the mean AD genetic risk score (GRS) of their CU members using effect sizes for 25 established European AD risk loci. Regions exhibiting significant or suggestive increases in the LOD* score during OSA were further evaluated using single-variant and interaction association tests in a sample of 715 CU and 460 CI participants. Results: Significant evidence of linkage following OSA adjustment was detected on chromosome 2 at SNP rs6719884 (~59.0 Mb) within the lincRNA LINC01122 (LOD* = 3.08), suggesting a shared genetic factor influencing preserved cognition in high-risk individuals. Additionally, a significant interaction effect was observed on chromosome 12 at SNP rs11063479 (~5.1 Mb) near the KCNA5 gene. The variant showed increased odds of being cognitively unimpaired in the high-GRS stratum (OR = 2.07) and decreased odds in the low-GRS stratum (OR = 0.70), indicating a potential synergistic effect with genetic risk. Conclusions: Our findings highlight specific genomic regions, particularly on chromosomes 2 and 12, that may harbor genetic loci contributing to preserved cognitive function in aged individuals at high genetic risk for AD. The identification of LINC01122 and KCNA5 as candidate genes underscores the potential role of brain-expressed lincRNAs and potassium channel genes in preserving cognitive function. These results contribute to the understanding of cognitive preservation and may inform future research on protective genetic mechanisms against cognitive decline. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was supported by the National Institutes of Health/National Institute on Aging grant R01AG058066, awarded to Jonathan L. Haines, Margaret Pericak-Vance, and William K. Scott. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Human subject approvals were obtained from the Institutional Review Boards (IRBs) at the University of Miami and Case Western Reserve University. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data referenced in this manuscript is available upon request and with principal investigator approval by reaching out to the primary author.

For clinical trials or patient care, reports from a person familiar with the trajectory of a participant’s cognitive and functional performance (i.e., proxies) may improve adjudication of events, such as mild cognitive impairment and dementia. Proxies offer a unique perspective on cognitive status that is different from what is captured through standard cognitive examinations. Clinical trials in which cognitive status is adjudicated, such as the Systolic Blood Pressure Intervention (SPRINT) trial, provide information about the contributions and consistency of proxies throughout extended follow-up. SPRINT participants named proxies and relationship to them at study onset. Proxies provided information for the Functional Activities Questionnaire and Dementia Questionnaire. We collapsed proxy relationships into seven categories and evaluated the proportion of proxies in each category at baseline and how frequently the same proxy was retained to the last visit. We explored associations between proxy relationship and various baseline demographics and examined the association between not having a proxy, as well as proxy relationship, and adjudicated outcome. Of the 9,361 randomized SPRINT participants (35.6% female, mean age 67.9 years), 7,586 (81%) participants listed a proxy relationship from which we identified 7 categories: spouse/partner (51.7%), child (23.6%), sibling (8.7%), other family member (6.2%), and unrelated (8.8%). Male participants were more likely to name a spouse as their proxy (64%) while female participants more likely to name a child (42%). The overall consistency of proxy continuation between the baseline and final SPRINT visit (mean 6.9 years) was 90.7%. Proxy consistency from first visit to last visit for a child was 94.8%, spouse/partner (91.9%) brother/sister (87.5%), other family member (82.4%), non-related (81.2%), and parent (78.2%). Adjudications that resulted in ‘Cannot Classify’ were greatest for proxies who were parents (15%) followed by none (12%), sibling and grandchild (9%), child and unrelated (7%), spouse and other family (6%). The majority of proxies in SPRINT were immediate family members (spouse, child, or sibling). Over 90% of identified proxies at baseline continued to be available over a mean of almost 7 years of follow-up. Not having a proxy available led to a higher rate of ‘cannot classify’ adjudications.

OBJECTIVE:Even with recruitment efforts for racial and ethnic minorities in dementia research, there is still underrepresentation in these communities. Targeting barriers and facilitators to research participation, we developed and tested a culturally tailored communication approach tailored for Hispanics. METHODS:An iterative process informed by input from the minority advisory board of an Alzheimer's Disease Research Center, developed 2 brief health communication videos, featuring Hispanic actors/Spanish language sub-titles. The experimental video (POWER) focused on barriers, facilitators, and readiness to participate in dementia research. The control video focused on education only. A randomized prospective survey compared POWER vs. control. While race or ethnicity were not inclusion criteria for enrollment, we oversampled Hispanic and non-white communities. We examined change pre- vs. post-video on dementia knowledge, cumulative barriers, and facilitators to research participation, as well as change in research readiness measured by the Transtheoretical behavior change model. RESULTS:The analyzable sample (N = 184) had a mean age of 40.0 (SD = 13.2) years, 57.4% (n = 105) female, 47.2% (n = 85) non-white, 21.2% (n = 39) Hispanic, with 88 individuals randomized to POWER and 96 to control. Unadjusted evaluation of change from pre- vs. post-video showed significant improvements in dementia knowledge, research facilitators and research barriers (all ps < .001) but no significant difference between POWER vs. controls. Adjusted for age, gender, race, ethnicity and education, only change in dementia knowledge remained significantly improved for the group as a whole, with no significant difference between POWER vs. controls. In the entire sample, Hispanics had significantly more improvement in research readiness (r = .217, p = .003). Exploratory analysis of positive change predictors in those randomized to POWER and to control suggests Hispanics in POWER may be at a disadvantage with respect to dementia knowledge (r = -.248, p = .02) and research facilitators (r = -.342, p = .001). CONCLUSIONS:Health communications can improve dementia knowledge across diverse communities.

Apathy in Alzheimer’s disease improves with methylphenidate (MPH) but treatment response was found to vary depending on clinical factors. Here, we explored whether underlying biological factors assessed by blood-based biomarkers of neurodegeneration, inflammation and oxidative stress affect apathy treatment response. A subset of participants from the Apathy in Dementia Methylphenidate Trial 2 (ADMET 2) were included in this study whose blood samples were available at baseline and at the 6-month treatment completion. Apathy was assessed with the Neuropsychiatric Inventory apathy subscale (NPI-A, range: 0-12). Blood concentrations of (i) neuronal damage: neurofilament light (NFL) and S-100B (available at baseline only), (ii) inflammation: interleukin (IL)-6, IL-10, Tumor Necrosis Factor-alpha (TNFα), and (iii) oxidative stress: lipid hydroperoxide (LPH), 4-hydroxynonenal (4-HNE), 8-isoprostane (8-ISO) were obtained with ELISA assays. Biomarkers were normalized by log transformation and pareto scaling. Predictive value of biomarkers was assessed by examining differences in treatment response between each biomarker tertile level. We also assessed whether biomarkers improved predictive models for established clinical predictors. Monitoring value was assessed by linear mixed models with NPI-A as the dependent variable and interaction between biomarker and time or biomarker and treatment as the independent variable. Among 55 participants (MPH: 24, age: 75.4 years [standard deviation (SD): 7.6], MMSE: 19.9 [SD: 4.9]) at baseline and 49 at the 6 month end point, the change in NPI-A showed a greater than 2-point difference between tertiles of NFL (6.8 points), TNFα (4.2 points) and 8-ISO (5.5 points) (Fig. 1). Treatment response prediction improved by adding NFL with cholinesterase use (likelihood ratio test[lrt]: 4.6, p: 0.03), presence of agitation (lrt: 4.4, p: 0.04) or presence of anxiety (lrt: 4.5, p: 0.04); no added value was found with TNFα and 8-ISO. As a monitoring biomarker, TNFα (but not NFL and 8-ISO) levels over time were associated with NPI-A score (t: 2.69, p: 0.009). Blood-based biomarkers of neurodegeneration, inflammation and oxidative stress are associated with apathy and affect treatment response, indicating potential predictive and monitoring value. Peripheral inflammation (TNFα) may have added value along with clinical predictors of response.

Late-onset Alzheimer Disease (LOAD) shares multiple pathologic features and genetic risk factors with Age-related Macular Degeneration (AMD). Amyloid-beta (Ab) forms amyloid plaques in the brain and aggregates with other proteins and lipids to form drusen deposits in the retina of AMD eyes. CFH and HTRA1 , genes coding for Ab-processing complement proteins, are the strongest genetic risk factors for AMD, but the association with LOAD has been equivocal. In addition, the APOE e4 allele, LOAD's strongest genetic risk factor, has the opposite effect (e.g. is protective) for AMD. Therefore, we investigated whether the strongest genetic risk factors for AMD, CFH and ARMS2/HTRA1 also influence risk of LOAD. Utilizing our large dataset of mid-Western Amish individuals, we performed single nucleotide polymorphism (SNP) association analysis on the ARMS2/HTRA1 and CFH loci to determine their association with LOAD. This analysis included 152 LOAD cases and 746 cognitively unimpaired controls, all evaluated by consensus review of clinical test results. Those with known AMD were excluded from this study. Our preliminary results found no significant association between LOAD and the individual SNPs defining the CFH or ARMS2/HTRA1 loci. As these genes are in regions of strong linkage disequilibrium, these SNPs define a small set of extended haplotypes, which have known differential impact on AMD. Single SNP association analyses did not expose any significant associations between LOAD and single SNPs at the CFH or ARMS2/HTRA1 loci. Examining the haplotype association with LOAD will allow for increased power and better understanding of the risk these two loci confer to LOAD.

Plasma amyloid-beta (Aβ) 42/40 ratio and phosphorylated tau 181 (pTau181) are promising blood biomarkers for AD. Compared to heterogenous clinical phenotypes, they are more objective and proximal to the pathological hallmarks of Aβ plaques and tau tangles. Biomarker-guided clustering using Aβ42/40 and pTau181 can potentially establish subpopulations that share similar mechanisms of AD and treatment responses. Plasma biomarkers were measured using Simoa™ Neuro-3Plex, 4Plex, and pTau181 Advantage V2 assays. To eliminate potential confounding effects, age, sex, and study center were regressed out of Aβ42/40 and pTau181 using a quadratic regression model. Adjusted biomarkers were then normalized for unsupervised K-means clustering, with the optimal number of clusters determined by the elbow method and Silhouette score. To interpret the cluster profiles, we explored the differences in demographics and clinical features between clusters. We also examined the association between clusters and neuropsychological tests adjusting for age, sex, study center, APOE e4 alleles, and diagnosis. We analyzed plasma biomarkers from 593 Amish individuals (age ³ 60 years old) living in Ohio and Indiana. 62% were females, and the average age was 81.7 ± 5.7 years. Utilizing plasma Aβ42/40 and pTau181, the clustering approach yielded six distinct clusters (N = 92, 95, 94, 152, 75, and 85) whose composition was driven by varying burdens of amyloid and tau pathology. There was no significant difference in proportion of cognitive impairment or of family structure across clusters. As expected, the low Aβ42/40 and high ptau cluster (Cluster 6) featured a significantly higher proportion of APOE e4 carriers than other clusters combined (51% vs 22%, p = 0.002). No significant associations were found between clusters and neuropsychological tests. The integrated analysis of plasma Aβ42/40 and pTau181 in the Amish established six clusters with varying levels of amyloid and tau burden, suggesting possible differences that need to be further explored. Examination of potential genetic or pathophysiological differences across the clusters are underway.

Studies of older adults with exceptional cognitive performance can enhance understanding of the mechanisms that protect against Alzheimer's disease (AD). Cognitive SuperAgers (SA) are individuals aged 80 and above with above-average episodic memory performance exceeding norms for middle-aged adults. This study integrates family- and association-based analytical approaches to identify genetic variants associated with SA in the Midwestern Amish population. A comprehensive neuropsychological evaluation was conducted among adult Amish participants ( N  = 515). SA were defined as those aged ≥ 80 with episodic memory task performance at or above the mean for ages 35-44, and non-episodic memory tasks within one standard deviation of the mean or better for the participant's age ( N  = 83). SA were grouped into 16 pedigrees for parametric and non-parametric linkage analysis allowing for locus heterogeneity in MERLIN. Variants located in regions exhibiting HLOD or LOD* scores ≥ 3 were tested for association with SA in GENESIS. Comparison groups included cognitively unimpaired, age-matched non-SA individuals (CU 80+, n  = 157) and individuals with AD ( n  = 40). Significance thresholds for each region were determined using SimpleM, which estimates the number of independent tests in the presence of high linkage disequilibrium. Linkage analysis identified HLOD scores > 3 on chromosomes 1 (HLOD = 3.10, GRCh38 44.6 Mb), 2 (HLOD = 3.92, 202.9 Mb), 7 (HLOD = 3.14, 30.2 Mb), 16 (HLOD = 3.18, 22.7 Mb), and 20 (HLOD = 3.71 16.7). Regional analysis revealed significant associations for eight correlated variants in the HIVEP3 gene on chromosome 1, comparing SA to AD (peak signal at rs12734651, OR = 0.24, p  = 6.46 x 10 -6 ). These variants were nominally associated when comparing SA to CU 80+ (rs12734651, OR = 0.61, p  = 0.032). This study identified variants in HIVEP3 associated with SA. Previous studies have linked variants in HIVEP3 to increased risk of AD, as well as with hippocampal volume and cognitive trajectories in unimpaired adults, suggesting that variants in HIVEP3 may influence both AD risk and cognitive performance in unimpaired individuals. These findings indicate that HIVEP3 represents a plausible candidate for further investigation into the mechanisms promoting exceptional cognitive performance in older adults.

Late-onset Alzheimer disease (LOAD) is the most common form of dementia among adults ≥65 years of age. Known risk factors include female sex, increased age, mild cognitive impairment (MCI), and LOAD-associated genetic risk alleles, most notably APOE e4. Recent evidence implicates the adaptive immune system as an important component of amyloid-β plaque clearance and suggests, in limited sample sizes, LOAD-associated immune profiles detectable in blood. We characterized somatic T-cell receptor (TCR) sequence diversity profiles from DNA extracted from blood (99%) and saliva (1%) in Ohio Amish participants with LOAD+MCI ( n  = 22), non-LOAD ( n  = 35), and an unclear diagnosis ( n  = 12). Sequencing was performed using Adaptive Biotechnologies immunoSEQ targeting the beta chain, resulting in >160,000 productive templates and >100,000 productive rearrangements. TCR beta chain sequences were characterized using Simpson's productive clonality, which ranges from 0 to 1 representing diverse and completely even sequences (e.g., 0) to monoclonal or single dominant clone (e.g., 1). We used productive Simpson clonality as a measure of TCR diversity in our supervised logistic regression. To assess the pairwise repertoire similarities, we focused on the Morisita-Horn index, which accounts for clonotype abundance while maintaining robustness against extreme values. We applied an unsupervised machine learning (ML) approach, fuzzy C-means clustering, to identify potential patterns specific to disease status. Participants did not differ significantly based on sex. LOAD+MCI participants were slightly older at last clinical exam than non-LOAD or unclear participants (83.9 vs 81.5 and 81.2 years, respectively; chi-square, p  = 0.058). We observed significantly higher TCR sequence diversity in the non-LOAD group compared to the LOAD-MCI group ( p  = 0.027). However, the association was not significant after adjusting for age and sex. Clustering results showed moderate agreement with clinical diagnoses (adjusted rand index up to 0.4), and incorporating APOE genotypes enhanced the performance. The addition of age as a variable, which has been demonstrated to be related to both LOAD risk and TCR diversity, reduced the clustering agreement slightly. Decreased TCR diversity is marginally associated with having LOAD or MCI. Our ongoing work focuses on applying ML approaches to TCR CD3 amino acid sequences to identify disease-associated clonotypes and develop predictive models for LOAD diagnosis.

Objective: Even with recruitment efforts for racial and ethnic minorities in dementia research, there is still underrepresentation in these communities. Targeting barriers and facilitators to research participation, we developed and tested a culturally tailored communication approach tailored for Hispanics. Methods: An iterative process informed by input from the minority advisory board of an Alzheimer's Disease Research Center, developed 2 brief health communication videos, featuring Hispanic actors/Spanish language sub-titles. The experimental video (POWER) focused on barriers, facilitators, and readiness to participate in dementia research. The control video focused on education only. A randomized prospective survey compared POWER vs. control. While race or ethnicity were not inclusion criteria for enrollment, we oversampled Hispanic and non-white communities. We examined change pre- vs. post-video on dementia knowledge, cumulative barriers, and facilitators to research participation, as well as change in research readiness measured by the Transtheoretical behavior change model. Results: The analyzable sample (N = 184) had a mean age of 40.0 (SD = 13.2) years, 57.4% (n = 105) female, 47.2% (n = 85) non-white, 21.2% (n = 39) Hispanic, with 88 individuals randomized to POWER and 96 to control. Unadjusted evaluation of change from pre- vs. post-video showed significant improvements in dementia knowledge, research facilitators and research barriers (all ps < .001) but no significant difference between POWER vs. controls. Adjusted for age, gender, race, ethnicity and education, only change in dementia knowledge remained significantly improved for the group as a whole, with no significant difference between POWER vs. controls. In the entire sample, Hispanics had significantly more improvement in research readiness (r = .217, p = .003). Exploratory analysis of positive change predictors in those randomized to POWER and to control suggests Hispanics in POWER may be at a disadvantage with respect to dementia knowledge (r = -.248, p = .02) and research facilitators (r = -.342, p = .001). Conclusions: Health communications can improve dementia knowledge across diverse communities.

Mosaic loss of chromosome Y (mLOY) refers to acquired aneuploidy in a fraction of somatic cells. In aging men, this has been suggested as a possible biomarker for increased risk of numerous diseases, including Alzheimer’s disease (AD). We investigated mLOY estimated from whole genome sequencing (WGS) as a risk factor for AD in the Midwestern Amish, a founder population with homogeneous lifestyle, reducing the effect of confounding environmental factors. The calling of mLOY was performed using the Mosaic Chromosomal Alterations (MoChA) pipeline, utilizing long-range phase information to search for imbalances between maternal and paternal allelic fraction in a cell population. A loss was called when the slope of coverage over allelic deviation was -0.94. The cognitive status of each individual was assigned via consensus review of medical history and neuropsychological testing. The cognitively-impaired (CI) group combined AD, MCI and Unclear individuals and compared to the cognitively-unimpaired (CU) group. Individuals in 3 age groups (65-74, 75-84, ≥85) were included. To evaluate the association between mLOY and risk of developing CI in follow-up, we fit a Cox proportional hazards model associating mLOY to years of disease-free follow-up within individuals for whom blood was sampled prior to CI diagnosis. After extensive QC, 457 males (mean age = 80.48±5.12) were included. mLOY frequency increased with age (p = 0.029): 18.75% (65-74; n = 48), 31.86% (75-84; n = 317) and 39.13% (85+; n = 92). A subset of 372 males were assigned to the CU (n = 202) or CI (n = 170) group and mLOY was slightly higher in the CI group (26.2% in CU vs. 34.1% in CI; p = 0.099). Within 217 males for whom blood was sampled a priori , there were 48 subsequent CI events. mLOY was associated with an increased risk of CI diagnosis with hazard ratio (HR) = 1.90 (1.03-3.56, p = 0.04). After adjusting for the age of sampling, HR increased to 2.31 (1.23-4.36, p = 0.009). We assessed the impact of mLOY in males on the risks of CI. We observed the same trend as reported in other European descent populations: mLOY increased with age and the higher sensitivity with WGS data compared with array-based data. We found that carriers of mLOY had an increased risk of impairment.

INTRODUCTION:Alzheimer disease (AD) plasma biomarkers are noninvasive measures of the key amyloid beta (Aβ) and tau pathologies. Validation and generalization studies are needed to fully understand their potential for AD prediction and diagnosis in the elderly population. METHODS:In 1,067 Amish individuals aged ≥ 65, we measured plasma Aβ and tau to assess their relationships with AD-related outcomes. RESULTS:Among Amish individuals with AD, plasma p-tau181 was significantly higher ( p = 0.04), and plasma Aβ42/p-tau181 ratio was significantly lower ( p = 0.01) than cognitively normal individuals. The association of AD with elevated p-tau181 was driven by APOE ε4 carriers (OR = 6.02, p < 0.001). Cluster analysis identified two subgroups defined by differing Aβ and tau levels, with the high-risk cluster having more APOE ε4 carriers ( p < 0.001). DISCUSSION:Plasma biomarkers, particularly p-tau181, Aβ42/Aβ40, and Aβ42/p- tau181 ratio, are promising surrogate biomarkers for AD-related pathology and clinical outcomes in the Amish.

Apathy in Alzheimer’s disease (AD) is associated with cognitive impairment, particularly executive functions such as selective attention, making it unclear whether apathy should be a separate treatment target. Apathy in Dementia Methylphenidate Trial 2 (ADMET 2) is the largest and most recent trial assessing apathy and cognition. This analysis assessed whether changes in apathy correlated to changes in various cognitive domains in ADMET 2. In this multicentre, randomized, placebo-controlled trial, 200 participants with mild to moderate AD received 20 mg methylphenidate (MPH) or placebo (PLB) for 6 months. The Neuropsychiatric Inventory apathy (NPI-A) subscale measured apathy. Cognitive tests included Mini-Mental State Exam (MMSE), Hopkins Verbal Learning-immediate (HVLT-I) and delayed (HVLT-D), Digit Span forward (DF) and backward (DB), Trail Making (TMT A and B), Action Verbal Fluency (AV), Category Fluency (CF), and Boston Naming Test (BNT). Linear mixed models were conducted with cognitive change scores as the dependent variable and time and change in NPI-A as the independent variable, overall and in each treatment group. All models were adjusted for baseline cognitive test score and NPI-apathy, age, sex, diabetes, and treatment group. 199 ADMET 2 participants (131 (66%) male) were included. For all participants, worsening apathy was associated with worsening MMSE (B (SE) = -0.10 (0.03), p = 0.003), CF (B (SE) = -0.13 (0.04), p = 0.0009), and HVLT-I (B (SE) = -0.13 (0.05), p = 0.005). In the MPH group (n = 98), worsening apathy was associated only with worsening CF (B (SE) = -0.21 (0.06), p = 0.0008). In the PLB group (n = 101), worsening apathy was associated with worsening MMSE (B (SE) = -0.13 (0.05), p = 0.006), HVLT-I (B (SE) = -0.30 (0.06), p = 0.000002), and HVLT-D (B (SE) = -0.06 (0.02), p = 0.002). Changes in apathy were not associated with performance on the remaining cognitive tests. Changes in apathy are associated with changes in cognition as part of the natural history of AD. However, this association is disrupted by MPH treatment and suggests that improvements in apathy in AD with MPH were not driven by cognitive changes. These results are consistent with the view that apathy as a syndrome is related to, but distinct from cognition.